Self-lubricating metal bearing and the like



' UNITED STATES PATENT OFFICE.

GEORGE G. DO'WER, OF WOMESTEB, MASSACHUSETTS, ASSIGNOR OI" ONE-HALF '10 GEORGE I. ALDEN, OF WORCESTER, MASSACHUSETTS.

SELF-LUBRICATING METAL BEARING AND THE LIKE.

Io Drawing.

To all whom it may concern:

Be it known that I, Gnoncn G. Down, a citizen of the United States residing at Worcester, in the county of Worcester and State of Massachusetts, have invented a new and useful Self-Lubricating Metal Bearing and the like, specification.

This invention relates to the so -called 011- less or self-lubricating metal bearings, bushings and the like in which the lubrlcant emplo ed consists of solid particles of lubricating material, as graphite, embedded in the metal of which the bearing is made.

The principal objects of this invention are to provide for the production of a hearing or the like or a body of composition suitable for producing a bearing or bushing in which particles of uncoated, untreated, commercially pure graphite will be interspersed throughout the metal with substant1al u n1- formity; to provide a bearing composition which can be made of any bearing metal or alloy, even those having a high melting temperature and without resorting to the use of coating metals, chemicals, fluxes or the like for treating the graphite; to pro-- them throughout the mass thereof.

- One of the improvements which has been introduced in this class ofbearings has been the coatin' of the graphite particles with copper be ore mixing them in the molten bearing metal. This was limited to the use of bearing metals which would melt at a temperature below that. of the copper for otherwise the copper would melt and thus free the particles of graphite. It is also objectionable because it impairs the value of the metal bearing itself owing to the pres- Speciflcation of Letters Patent.

Application filed Kay 10, 1980. Serial Io. 880,107.

of which the following is a' Patented Sept. 6, 1921.

ence of two metals of different properties and involves what I find to be entirely unnecessary expense. Traces of the acids emwhen in fluid condition. I have found that I can produce a self-lubricating bearing which can be made of any suitable metal or alloy, even iron, and commercially pure graphitewithout danger of the graphite risingl 'to the top of the castin y preferred method 0? procedure is as follows :--The metal or alloy, whether it is soft or hard, is divided up into small particles and mixed with commercially pure uncoated free graphite, in the usual fine flake form for example. An intimate mixture is formed in which the graphite is interspersed uniformly throughout the metal, or in other words is located in the metal in substantially the way in which it is desired to have it in the finished article. Then the mixture is subjected to pressure preferably in a mold shaped to produce the article desired. This consolidates the metal and graphite somewhat. The pressure may run as high as from one hundred to one thousand pounds per square inchbut I do not wish to be limited to any specified amount. Then the mixture is heated until the metal fuses, still under pressure, and then immediately cooled to cause it to set in the mold be fore the graphite can rise in the mold and.

gather about the upper surfaces thereof. In other words I introduce into a mold the graphite and bearing metal or alloy, both in comminuted form and thoroughly mixed, in a solid or unmelted state, subject it to pressure, melt the metal and then cool it before the graphite segregates. The metal can be reduced to thisfine condition by granulating or otherwise. The proportions and amount of raphite can be varied Within wide limits, but I usually prefer to have the graphite constitute substantially from 5% to 50% of the whole mixtureby volume.

The process is very short and inexpensive and the cost of the bearing is reduced over those produced by processes recentl introduced because it eliminates all prellminary treatment of the graphite; It permits of the use of metals or alloys having a high melting point, such as bronze and even cast iron, which it may be desirable to use for special purposes. The invention is capable of uni-,

versal application. for all bearing metals.

A uniform distribution of the graphite in the metal is secured and the metal is substantially free from cavities and blow holes, The product is formed of pure materials, the graphite especially being in its commercially pure form without treatment by acids or prior coatin with metal, in fact it can be, and preferab y is, used in the flake form in which it is obtainable on the marhot. The product can be machined or worn down without damage to it and especially without causing a variation in the amount of graphite appearing in the surface. During the process, there is no acid used which can renderits surfaces brittle and thus impair the wearing surface of the bearing or render the machining of its surfaces practically impossible.

Although I have specified a single series of steps in carrying out the process, I am aware of the fact that modifications can be made therein by any person skilled in the art withoutdeparting from the scope of the invention as expressed in the claims. Therefore, I do not wish to be limited in these respects, but what I do claim is:

An oillessbearing formed from bearing metal, and commercially pure graphite, mixed together While both are solid and in a fine state of subdivision and free from all 1 GEORGE G. DOWER: 

